Variable-power segmented laser welding process regulation strategy and weld forming analysis

Autogenous laser welding experiments were conducted on 2.0 mm-thick 5052 aluminum alloy sheets to investigate an along-weld segmented-power-regulation strategy. With the same design average laser power used as the control basis, the welding speed held constant, and the total waveform period fixed across all segmented conditions, the effects of power amplitude, segment number, and laser mode on weld formation, microstructure, and microhardness distribution were examined. Three-, four-, five-, and six-segment schemes were compared under continuous-wave and pulsed-wave conditions, and thermocouple measurements were used to calibrate a thermomechanical model for the conventional continuous-wave, three-segment, and four-segment conditions. The ±2% power-amplitude condition provided a favorable balance among surface morphology, weld dimensions, and penetration stability. Increasing the segment number from three to four produced more regular weld profiles, more refined and uniform microstructural features, and a more uniform microhardness distribution. Further increases to five and six segments produced no consistent additional improvement, indicating diminishing marginal benefits beyond four segments. At the same segment number, continuous-wave welding generally produced more regular surface and cross-sectional morphologies and greater microstructural homogeneity than pulsed-wave welding. The thermomechanical simulations showed that the three- and four-segment conditions exhibited lower maximum equivalent-stress values relative to conventional continuous-wave welding. Overall, under the investigated conditions, the four-segment scheme provided a comparatively favorable balance between regulation effectiveness and process-control complexity.